msem-instigator

Whenever you tap an artifact or land for mana, add one mana of any type that permanent produced.

Each opponent sacrifices a creature or planeswalker. If you own a foretold card in exile, you gain 4 life.

You may have Imitator of Success enter as a copy of any creature on the battlefield, except it has no mana cost and base power and toughness 1/1 if it's a token.
Successor {1}{U}{U} ({1}{U}{U}, Exile this card from your graveyard: Create a token that's a copy of this card, except it has no mana cost and base power and toughness 1/1. Succeed only as a sorcery.)

Distribute three +1/+1 counters among any number of creatures you control.
Metamorph {1}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

Destroy target artifact.
Reprise {R} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)

Whenever a face-down creature you control attacks, defending player loses 1 life.
{2}, Discard a card: Manifest the bottom card of your library. Activate only once each turn. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Enchant creature
Enchanted creature gets +1/+1, has flying and lifelink, and is a legendary artifact in addition to its other types.

Exile target creature card from a graveyard. Create a token that's a copy of that creature, except it's a colorless artifact. (It's not a creature.)

Defender
When Immured Fiend enters, target opponent discards two cards.

Exile target creature or enchantment. You gain 3 life.

As an additional cost to cast this spell, discard a nonland card.
All creatures get -X/-X until end of turn, where X is the discarded card's mana value.

Enchant creature
When Imperative Blessing enters, draw a card.
Enchanted creature gets +2/+2.

Flying
When Imperator Namuzzar enters, search your library for an artifact or enchantment card, reveal it, put it into your hand, then shuffle.
Civilized — Lammasu you control get +2/+2 and have hexproof as long as you control an artifact, a creature, and an enchantment.

First strike, vigilance
Partner with Commander Hyctaleon (When this creature enters, target player may put Commander Hyctaleon into their hand from their library, then shuffle.)
At the beginning of your upkeep, you may search your library for a Soldier card, reveal it, put it into your hand, then shuffle.

Draw three cards.
Lifecycle {3} ({3}, Discard this card: Create two tapped 1/1 colorless Elemental creature tokens.)

When Imperfect Stone enters, mill three cards.
{T}: Add one mana of any color.

When Imperial Artisan enters, draw three cards, then put two cards from your hand on top of your library in any order.

All creatures get -2/-2 until end of turn.
Civilized — Instead only creatures your opponents control get -2/-2 until end of turn if you control an artifact, a creature, and an enchantment.

At the beginning of your upkeep, scry 2.
Reveal the top card of your library: If a creature card with flying was revealed this way, Imperial Chimera gains flying until end of turn. The same is true for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance.

If a source an opponent controls would deal 2 or more damage to you, prevent 1 of that damage.
Civilized — Instead prevent all but 1 of that damage if you control an artifact, a creature, and an enchantment.

When Imperial Diplomats enters, if it's not a token, create a token that's a copy of it, except it has no mana cost.
{T}, Tap an untapped creature you control: Draw a card, then discard a card.

First strike
When Imperial Dragoon enters, target creature gets +2/+0 until end of turn.

Trample
If a creature in Imperial Guardian's pack would deal damage to a permanent or player, it deals twice that much damage instead. (Two or more creatures you control with equal power are in a pack.)

Mill four cards, then return a noncreature card from your graveyard to your hand.

Trample
Art of war — At the beginning of your end step, if Imperial Legion dealt damage to an opponent this turn, put two +1/+1 counters on it.